A number of researches have been conducted to eliminate interference from occurring in a wireless communication system. For example, researches to eliminate intra-cell interference and inter-cell interference between cells have been conducted to improve communication quality. However, although communication quality with respect to the whole cell may be improved by eliminating the intra-cell interference and inter-cell interference, communication quality of a user in an edge of the cell may not equal that of a user in a center of the cell even with eliminating those interferences, since a data transmission rate of the user in the edge of the cell may be lower than that of the user in the center of the cell.
To improve the data transmission rate of the user in the edge of the cell, improving a cell capacity may be required. A multi input multi output (MIMO) communication method has been the focus of attention as a core technology to improve the cell capacity. To improve the cell capacity through the MIMO communication method, establishing a plurality of antennas in a base station may be required. However, establishing a plurality of antennas in a terminal may be limited by space and cost. As such, a multi-user MIMO communication system has been proposed where the number of antennas in a base station is greater than the number of antennas in a terminal. In the multi-user MIMO communication system, a transmitting end may be required to be aware of channel information of each receiving end. However, the transmitting end may not obtain channel information of every receiving end due to a characteristic of a time-varying channel and overhead caused by a channel feedback.
As an example, where a transmitting end considers many antennas, the number of terminals that may be simultaneously supported increases. In this case, since it may be impractical that the transmitting end receives complete channel information feedback of every receiving end. Accordingly, there is a need for an improved multi-antenna technology, for example, a multi-antenna technology where a transmitting end may not require channel information feedback of a receiving end.